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Digital Camera Forensics

...a stunning new technology in development at Binghamton University, State University of New York, that can reliably link digital images to the camera with which they were taken, in much the same way that tell-tale scratches are used by forensic examiners to link bullets to the gun that fired them.

This would allow forensic examiners to link digital images to digital cameras, by examining a form of noise in the images that resembles a fingerprint. There are some limitations, the examiner would have to have multiple other images taken by the camera to compare with, or understandably, the camera itself.

Other interesting points in the article include:

...the absence of the expected digital fingerprint in any portion of an image that provides the most conclusive evidence of image tampering.

In the near future, Fridrich's technique promises to find application in the analysis of scanned and video imagery. There it can be expected to make life more difficult for forgers, or any others whose criminal pursuits rely on the misuse of digital images.

I've read several reports on this technology and became instantly intrigued. I called a few friends over at NIST and sure enough, this is the real McCoy. I'm heading to the first forensics course offered on this technique.

--TH13

Our scars have the power to remind us that our past was real. -- Hannibal Lecter.
Talent is God given. Be humble. Fame is man-given. Be grateful. Conceit is self-given. Be careful. -- John Wooden

In the near future, Fridrich's technique promises to find application in the analysis of scanned and video imagery. There it can be expected to make life more difficult for forgers, or any others whose criminal pursuits rely on the misuse of digital images.

But give it some time and the criminal scene will most likely find a new technique to get around it somehow..

But it does indeed sound like something very interesting to read more about.

But give it some time and the criminal scene will most likely find a new technique to get around it somehow..

edit the image before posting to your kiddy porn friends.. ie a little blur a sharpen,, convert from TIFF to JPG, a de-speckle or two.. .. oh and dont use the same technique on each image.. probably pay to edit your images with different progs and on different computers... or better yep replace your camera every 1 or 2 hundred images, destroy the old camera.. change brands of memory cards..hmmmm better replace memory cards every few hundred images as well.. BURN the old cards..

"Consumer technology now exceeds the average persons ability to comprehend how to use it..give up hope of them being able to understand how it works." - Me http://www.cybercrypt.co.nr

Quite a few eclectic sports photographers profile the noise profiles of their cameras all of the time with several applications such as NoiseNinja, Noiseware, or pre-programmed profiles built into various RAW converters such as C1-Pro, Pixmantic RawShooter, or Adobe Camera Raw / DNG Converter. It is well known that a given camera model has a paticular 'look' to its noise characteristics. Their goal is to remove / hide / blur the noise their camera naturally produces so they can have a nice smooth image of an athlete catching a football, etc. (they say it prints better...I run grainy B&W images in dungeons known as gyms in the newspaper just fine though). Personally I think a few people take it too far producing images that definately look unrealistic and blotchy...but that's another story...

As far as taking an arbitrary image from the internet and figuring out whose camera took it...you're generally working with a 640x480 pixel image that was produced by resizing a 2560x1920 pixel image. It is 4x smaller in each dimension than the original image, so you're working with 1/16th the original surface area of the image, or about 6.25% of the original image. The rest of the data was dropped, and whatever emerges is just an estimation from combining neighboring pixels. In short, noise is hidden, and you'll be hard-pressed to get very far in figuring out whose camera took the picture...

Basically there are many ways to 'hide' a paticular camera's signature. This software doesn't take an arbitrary image on the Internet and determine whose camera it was taken with (there's too many cameras out there, too few pixels in an image posted online). What it does is let you take your digital image and your camera to court, and show (hopefully beyond a resonable doubt) that your image's content was not edited in photoshop after taking the picture, ie., that the image was taken with that camera.

And on the scenario proposed by the article (which is a shocking scenario, though I don't see anything authoritive saying it was actually used in such a case)...by the time law-enforcement confiscates stuff, I have no idea how much impact saying "it was taken with this camera" has when there is probably already a mountain of evidence showing that the crime(s) took place. I'd imagine that other evidence for the most part would say the same thing. But it is nice to think that this kind of analysis will one day be used to further prove beyond a shadow of a doubt that the guilty are infact guilty of their crime(s).